888 Acne. 



through the orifices of the hair follicles or sebaceous glands, or 

 are rubbed into them. According to Frick mechanical influ- 

 ences only play the jDart of accidental causes in these cases. 



The disease occurs in those parts of the body which are 

 frequently exposed to mechanical influences, especially to rub- 

 bing, or which perspire readily. Such places are, in horses, on 

 the back and on the sides of the chest (friction l3y the saddle, 

 girth, traces) on the front of the chest and in the shoulder 

 region (rubbing by the collar and breast strap), in the croup and 

 tail region (friction by the breeching and crupper), as well as 

 on the head (mechanical friction from the halter). In dogs 

 the forehead, the cheeks, the bridge of the nose and the external 

 surfaces of the limbs are favorite spots for acne, because these 

 parts are preferably rubbed by the muzzle or come in contact 

 with the hard ground. 



The disease, which was studied closely by Bartke, Qualitz, Steffens, 

 Grammlich, v. Hennings, Kalkoff, and Kupfer under the name of sweat 

 eczema (heat pox) of riding horses, is an acne-like affection of the skin, 

 especially prevalent in the military horses of the Prussian Army since 

 the introduction of the new army saddle (according to Kupfer 50 horses 

 on an average in each regiment were affected in one summer), but it is 

 also observed when other saddles are used. The connection between the 

 frequency of this trouble and the introduction of the new army saddle, 

 is found in the fact that the trees of the new saddle are longer, and the 

 wallet is put further back, extending to the sensitive lumbar region, 

 Avhich on motion, and especially in walking, makes decided transverse 

 motions and furnishes much opportunity for friction between the skin 

 and the wallet. Saddles which do not fit well to the trees and which 

 are weighted too heavily, too much stirrup riding, lack of cleanliness in 

 the saddle region are also of importance. The chief effect is due to 

 friction, for the trouble does not occur under the saddle itself, but at 

 the back of the pannel and flap. The causal action of sweat and dust 

 is sho^\ai by the fact that the disease is observed almost exclusively in 

 summer. Horses with bad conformation and weak tottering gait are 

 apparently especially inclined to the disease. 



At times an extensive outbreak of acne occurs in horses 

 over the whole body in the warm summer weather (socalled sum- 

 mer rash) when the animals perspire profusely at work. 



The checking of glandular secretion by obstruction, by dirt, 

 of the orifices of the sebaceous glands or of the opening of the 

 hair follicles, possibly also by medicines rubbed on the skin 

 may, according to Veiel, occasion acne in such a manner that 

 the glandular tissue becomes mechanically irritated as a result 

 of tiie dried secretion. It cannot be denied, however, that the 

 bacteria which are usually present on the skin, or that products 

 of disintegration formed under the influence of the bacteria, 

 play an active part in the causation of acne. 



Whether aene which occurs occasionally after the application of certain medic- 

 aments such as tar, petroleum, paraffine, vaseline, also after continued employment 

 of creolin or lysol solution in wound treatment, is to be taken as due to the 



